Rotation angle estimation module for sensorless vector control of pmsm

ABSTRACT

A rotation angle estimation module is provided. The rotation angle estimation module includes: a fixed flux instruction estimation unit calculating a rotating flux (λ sd , λ sq ) and a fixed flux instruction (λ sα *, λ sβ *) based on a rotation angle θ and the current (I sα , I sβ ) of a fixed coordinate system; a fixed flux estimation unit calculating a fixed flux (λ sα , λ sβ ) based on the voltage (V sα , V sβ ) of the fixed coordinate system, and the current (I sα , I sβ ) and fixed flux error (Δ sα , Δ sβ ) of the fixed coordinate system; a fixed flux error estimation unit using the fixed flux instruction (λ sα *, λ sβ *) and the fixed flux (λ sα , λ sβ ) to calculate the fixed flux error (Δ sα , Δ sβ ) and feed the errors back to the fixed flux estimation unit; and a trigonometric function calculation unit calculating the rotation angle θ based on the rotating flux (λ sd , λ sq ) and the fixed flux (λ sα , λ sβ ).

CROSS-REFERENCE TO RELATED APPLICATIONS

Pursuant to 35 U.S.C. §119(a), this application claims the benefit ofearlier filing date and right of priority to Korean Patent ApplicationNo. 10-2014-0051180 filed on Apr. 29, 2014, the contents of which areall hereby incorporated by reference herein in its entirety.

BACKGROUND

The present disclosure relates to a sensorless vector control system ofa permanent magnet synchronous motor (PMSM), and more particularly, to arotation angle estimation module for sensorless vector control of aPMSM.

In general, information on the speed and location of a rotor is neededto control drive and control a synchronous motor, and a separatelocation sensor, such as an encoder or resolver is used for detectingthe location.

However, since a method of detecting the speed and location by using asensor has limitations in the complexity of hardware, an expensive cost,low reliability, and electrical noise, it is insufficient in economy andtechnology.

Since various sensorless vector control methods have been proposed inorder to solve such limitations, a sensor less control method mayestimate information on the speed and location of the rotor withoutinstalling a separate location sensor.

Typical sensorless vector control methods of a PMSM include a method ofusing counter electromotive force, a method of using a voltage model, amethod of using a model reference controller, a method of using a statusestimation module, a Kalman filter, non-linear control, and intellectualcontrol, but since they need a significant amount of calculation and anestimation error occurs in a low-speed region, there was a limitation inthat they are not easy to actually use.

Thus, there is a sensorless vector control method of a PMSM that maydrastically decrease the amount of calculation and minimize theestimation error.

SUMMARY

Embodiments provide a rotation angle estimation module and a sensorlessvector control system of a permanent magnet synchronous motor (PMSM)employing the module that decrease an amount of calculation for therotation angle estimation of the PMSM and minimize an estimation error,in the sensorless vector control of the PMSM.

In one embodiment, a rotation angle estimation module of a permanentmagnetic synchronous motor (PMSM) for sensorless vector control of thePMSM includes: a fixed flux instruction estimation unit calculating arotating flux (λ_(sd), λ_(sq))and a fixed flux instruction (λ_(sα)*,λ_(sβ)*) based on a rotation angle θ and the current (I_(sα), I_(sβ)) ofa fixed coordinate system; a fixed flux estimation unit calculating afixed flux (λ_(sα), λ_(sβ)) based on the voltage (V_(sα), V_(sβ)) of thefixed coordinate system, and the current (I_(sα), I_(sβ)) and fixed fluxerror (Δ_(sα), Δ_(sβ)) of the fixed coordinate system; a fixed fluxerror estimation unit using the difference between the fixed fluxinstruction (λ_(sα)*, λ_(sβ)*) and the fixed flux (λ_(sα), λ_(sβ)) tocalculate the fixed flux error (Δ_(sα), Δ_(sβ)) and feed the errors backto the fixed flux estimation unit; and a trigonometric functioncalculation unit calculating the rotation angle θ, a distance that arotor moves, based on the rotating flux (λ_(sd), λ_(sq)) and the fixedflux (λ_(sα), λ_(sβ)).

The trigonometric function calculation unit may finally calculate therotation angle θ and feeds a calculated angle back to the fixed fluxinstruction estimation unit.

The fixed flux instruction estimation unit may calculate the rotatingflux (λ_(sd), λ_(sq)) based on the current (I_(sα), I_(sβ)) of the fixedcoordinate system, the rotation angle θ, the inductance (L_(d), L_(q))of a rotary coordinate system, and the flux λ_(PM) of a permanentmagnet.

The fixed flux instruction estimation unit may compensate for therotation angle θ by using the rotating flux (λ_(sd), λ_(sq)) tocalculate a fixed flux instruction (λ_(sα)*, λ_(sβ)*).

The fixed flux estimation unit may receive the α axis voltage V_(sα) ofthe fixed coordinate system, the α axis current I_(sα) of the fixedcoordinate system, and the α axis flux error Δ_(sα) of the fixedcoordinate system to calculate an α axis flux change ratio dλ_(sα)/dt ofthe fixed coordinate system by using an equationdλ_(sα)/dt=V_(sα)−R_(s)I_(sα)+Δ_(sα)(R_(s): stator resistance), receivethe β axis voltage V_(sβ) of the fixed coordinate system, the β axiscurrent I_(sβ) of the fixed coordinate system, and the β axis flux errorΔ_(sβ) of the fixed coordinate system to calculate the β axis fluxchange ratio dλ_(sβ)/dt of the fixed coordinate system by using theequation dλ_(sβ)/dt=V_(sβ)−R_(s)I_(sβ)+Δ_(sβ)(R_(s): stator resistance),integrate the α axis flux change ratio dλ_(sα)/dt of the fixedcoordinate system to output the α axis flux λ_(sα), and integrate theoutput of the β axis flux change ratio dλ_(sβ)/dt of the fixedcoordinate system to output the β axis flux λ_(sβ) of the fixedcoordinate system.

The fixed flux error estimation unit may calculate the differencebetween the α axis flux instruction value λ_(sα)* of the fixedcoordinate system input from the fixed flux instruction estimation unitand the α axis flux λ_(sα) input from the fixed flux estimation unit,calculate the difference between the β axis flux instruction valueλ_(sβ)* of the fixed coordinate system input from the fixed fluxinstruction estimation unit and the β axis flux λ_(sβ) input from thefixed flux estimation unit, receive the difference from the α axis fluxλ_(sα) to adjust a gain and calculate the α axis flux error Δ_(sα) ofthe fixed coordinate system, and receive the difference from the β axisflux λ_(sβ) to adjust a gain and calculate the β axis flux error Δ_(sβ)of the fixed coordinate system.

The trigonometric function calculation unit 40 may find angels θ_(dq)and θ_(αβ) by the applying of a trigonometric function to the rotatingflux (λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)), respectively,and output the rotation angle θ based on the angles θ_(dq) and θ_(αβ).

The trigonometric function calculation unit 40 may receive the d axisflux λ_(sd) of the rotary coordinate system and the q axis flux λ_(sq)of the rotary coordinate system from the fixed flux instructionestimation unit to output the angle θ_(dq) of λ_(d q) based on the daxis by using a trigonometric function arctangent, receive the α axisflux λ_(sα) of the fixed coordinate system and the β axis flux λ_(sβ) ofthe fixed coordinate system from the fixed flux estimation unit tooutput the angle θ_(αβ) of λ_(αβ) based on the α axis by using thetrigonometric function arctangent, and find the difference between theangles θ_(dq) and θ_(αβ) to output the rotation angle θ.

In another embodiment, an operating method of a rotation angleestimation module of a motor for sensorless vector control of a PMSMincludes: calculating a rotating flux (λ_(sd), λ_(sq)) and a fixed fluxinstruction (λ_(sα)*, λ_(sβ)*) based on the current (I_(sα), I_(sβ)) ofa fixed coordinate system and a rotation angle θ; calculating a fixedflux (λ_(sα), λ_(sβ)) based on the voltage (V_(sα), V_(sβ)) of the fixedcoordinate system, and the current (I_(sα), I_(sβ)) and fixed flux error(Δ_(sα), Δ_(sβ)) of the fixed coordinate system, through a fixed fluxestimation unit; using the difference between the fixed flux instruction(λ_(sα)*, λ_(sβ)*) and the fixed flux (λ_(sα), _(sβ)) to calculate thefixed flux error (Δ_(sα), Δ_(sβ)) and feed the errors back to the fixedflux estimation unit; and calculating the rotation angle θ, a distancethat a rotor moves, based on the rotating flux (λ_(sd), λ_(sq)) and thefixed flux (λ_(sα), λ_(sβ)).

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram for explaining vector between the fixed coordinatesystem and rotary coordinate system of the rotation angle estimationmodule according to an embodiment.

FIG. 2 is a block diagram representing the general relationships betweenthe components of the rotation angle estimation module according to anembodiment.

FIG. 3 is a block diagram based on a circuit diagram of the rotationangle estimation module according to an embodiment.

FIG. 4 is a block diagram representing a status in which the rotationangle estimation module according to an embodiment is applied to atypical sensorless vector control system of a permanent magnetsynchronous motor (PMSM).

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following, the technical features of an embodiment are describedin detail with reference to the accompanying drawings.

FIG. 1 shows the principle of the sensorless vector control method of apermanent magnet synchronous motor (PMSM) according to an embodiment, byusing a vector diagram.

The vector control method divides and controls currents applied to themotor into a flux current Id_(se) and a torque current Iq_(se) based ona rotary coordinate system.

The vector control method of the PMSM fixes the flux current Id_(se) tomatch a rotor location θ, and applies the torque current Iq_(se) to thesensorless vector control of the PMSM.

In order to match the flux current Id_(se) with the rotor location θ,there is a need to acquire the rotor location θ from a location sensor.

FIG. 1 represents a flux relationship according to a fixed coordinatesystem αβ and a rotary coordinate system dq in the vector control of thePMSM, an axis used for a vector control system is divided into the fixedcoordinate system and the rotary coordinate system, the fixed coordinatesystem indicates a coordinate system having a coordinate axis notrotating but fixed, and the rotary coordinate system indicates acoordinate system that rotates at any angular velocity ω.

By using a flux value (λ_(α), λ_(β)) based on the fixed coordinatesystem αβ and a flux value (λ_(d), λ_(q)) based on the rotary coordinatesystem dq, it is possible to estimate the rotor location θ bysubtracting the angle θ_(d q) of λ_(d q) based on the d axis from theangle θ_(αβ) of λ_(αβ) based on the α axis.

An embodiment estimates a final rotor location by using stator fluxvector λ_(αβ) based on the fixed coordinate system αβ and rotor fluxvector λ_(d q) based on the rotary coordinate system dq along witharctangent tan⁻¹ and information on the estimated rotor location matchesthe location of an actual motor.

FIG. 2 shows a rotation angle estimation unit 100 estimating a rotationangle θ, a distance that a rotor moves, based on the vector diagram ofFIG. 1 and the rotation angle estimation unit 100 includes a fixed fluxinstruction estimation unit 10, a fixed flux estimation unit 20, a fixedflux error estimation unit 30, and a trigonometric function calculationunit 40.

The fixed flux instruction estimation unit 10 calculates a rotating flux(λ_(sd), λ_(sq)) and a fixed flux instruction (λ_(sα)*, λ_(sβ)*) basedon the current (I_(sα), I_(sβ)) and the rotation angle θ based on thefixed coordinate system αβ. In particular, the fixed flux instructionestimation unit 10 receives the current (I_(sα), I_(sβ)) and rotationangle θ of the fixed coordinate system αβ and uses a rotor flux equationto calculate the fixed flux instruction (λ_(sα)*, λ_(sβ)*).

The rotor flux equation firstly calculates a rotating flux (λ_(sd),λ_(sq)) and finally calculates the fixed flux instruction (λ_(sα)*,λ_(sβ)*) by using a calculation result.

The fixed flux estimation unit 20 calculates the fixed flux (λ_(sα),λ_(sβ)) based on the voltage (V_(sα), V_(sβ)) of the fixed coordinatesystem αβ, and the current (I_(sα), λ_(sβ)) and fixed flux error(Δ_(sα), Δ_(sβ)) of the fixed coordinate system. In particular, thefixed flux estimation unit 20 receives the voltage (V_(sα), V_(sβ)) ofthe fixed coordinate system αβ, and the current (I_(sα), I_(sβ)) andfixed flux error (Δ_(sα), Δ_(sβ)) of the fixed coordinate system αβ anduses a stator voltage equation to calculate the fixed flux (λ_(sα),λ_(sβ)) of the α and β axes.

The fixed flux error estimation unit 30 uses the difference between thefixed flux instruction (λ_(sα)*, λ_(sβ)*) and the fixed flux (λ_(sα),λ_(sβ)) to calculate the fixed flux error (Δ_(sα), Δ_(sβ)) and feeds theerrors back to the fixed flux estimation unit. In particular, the fixedflux error estimation unit 30 uses the difference between the fixed fluxinstruction (λ_(sα)*, λ_(sβ)*) output by the fixed flux instructionestimation unit 10 and the fixed flux (λ_(sα), λ_(sβ)) output by thefixed flux estimation unit 20 to calculate the fixed flux error (Δ_(sα),Δ_(sβ)) of the α and β axes and feeds the errors back to the fixed fluxestimation unit 20.

The trigonometric function calculation unit 40 calculates the rotationangle θ, a distance that a rotor moves, based on the rotating flux(λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)). In particular, thetrigonometric function calculation unit 40 performs calculation on therotating flux (λ_(sd), λ_(sq)) firstly calculated by the rotor fluxequation of the fixed flux instruction estimation unit 10 and the fixedflux (λ_(sα), λ_(sβ)) output by the fixed flux estimation unit 20 byusing trigonometric functions to find angles θ_(dq) and θ_(αβ),respectively.

When the angle θ_(dq) is finally subtracted from the angle θ_(αβ), it ispossible to calculate the rotation angle θ, a distance that a rotormoves, and a calculated rotation angle is fed back to the fixed fluxinstruction estimation unit 10.

The rotation angle estimation unit 100 continues to calculate therotation angle θ by feedback between the fixed flux error estimationunit 30 and the fixed flux estimation unit 20, between the fixed fluxestimation unit 20 and the trigonometric function calculation unit 40,and between the fixed flux instruction estimation unit 10 and thetrigonometric function calculation unit 40.

Each component of the rotation angle estimation unit is described indetail by using FIG. 3 that is a block diagram representing a particularcircuit configuration of the rotation angle estimation unit 100.

<Fixed Flux Instruction Estimation Unit 10>

The fixed flux instruction estimation unit 10 includes a first rotarycoordinate conversion unit 101, a second rotary coordinate conversionunit 102, a first rotating flux calculation unit 103, a second rotatingflux calculation unit 104, a first fixed coordinate conversion unit 105,and a second fixed coordinate conversion unit 106.

The first rotary coordinate conversion unit 101 receives the α axiscurrent I_(sα) of the fixed coordinate system and the rotation angle θin order to use a rotor flux equation and coordinate-converts into the daxis current value I_(sd) of the rotary coordinate system.

The second rotary coordinate conversion unit 102 receives the β axiscurrent I_(sβ) of the fixed coordinate system and the rotation angle θand coordinate-converts into the q axis current value I_(sq) of therotary coordinate system.

The first rotating flux calculation unit 103 receives the d axis currentI_(sd) of the first rotary coordinate conversion unit 101 and uses therotor flux equation, λ_(sd)=L_(d)I_(sd)+λ_(PM) (L_(d): d axis inductanceof the rotary coordinate system, λ_(PM): flux by a permanent magnet) tocalculate the d axis flux λ_(sd) of the rotary coordinate system.

The second rotating flux calculation unit 104 receives the q axiscurrent I_(sq) of the second rotary coordinate conversion unit 102 anduses the rotor flux equation, λ_(sq)=L_(q)I_(sq) (L_(q): q axisinductance of the rotary coordinate system) to calculate the q axis fluxλ_(sq) of the rotary coordinate system.

The d axis flux λ_(sd) and q axis flux λ_(sq) of the rotary coordinatesystem are input to the trigonometric function calculation unit 40.

The first fixed coordinate conversion unit 105 is a compensatorcompensating for a value coordinate-converted in order to use the rotorflux equation, compensates for the rotation angle θ by using the outputof the first rotating flux calculation unit 103 to coordinate-convertinto the fixed coordinate system, and outputs the α axis fluxinstruction value λ_(sα)* of the fixed coordinate system.

The second fixed coordinate conversion unit 106 compensates for therotation angle θ by using the output of the second rotating fluxcalculation unit 104 to coordinate-convert into the fixed coordinatesystem, and outputs the β axis flux instruction value λ_(sβ)* of thefixed coordinate system.

<Fixed Flux Estimation Unit 20>

The fixed flux estimation unit 20 includes a first fixed flux changeratio calculation unit 201, a second fixed flux change ratio calculationunit 202, a first integrator 203, and a second integrator 204.

The first fixed flux change ratio calculation unit 201 receives the αaxis voltage V_(sα) of the fixed coordinate system, the α axis currentI_(sα) of the fixed coordinate system, and the α axis flux error Δ_(sα)of the fixed coordinate system, term-converts the stator voltageequation, V_(sα)=R_(s)I_(Sα)+dλ_(sα)/dt(R_(s): stator resistance) intothe equation dλ_(sα)/dt=V_(sα)−R_(s)I_(sα)+Δ_(sα)(R_(s): statorresistance), and calculates the α axis flux change ratio dλ_(sα)/dt ofthe fixed coordinate system.

The second fixed flux change ratio calculation unit 202 receives the βaxis voltage V_(sβ) of the fixed coordinate system, the β axis currentI_(sβ) of the fixed coordinate system, and the β axis flux error Δ_(sβ)of the fixed coordinate system, term-converts the stator voltageequation, V_(sβ)=R_(s)I_(Sβ)+dλ_(sβ)/dt(R_(s): stator resistance) intothe equation dλ_(sβ)/dt=V_(sβ)−R_(s)I_(sβ)+Δ_(sβ)(R_(s): statorresistance), and calculates the β axis flux change ratio dλ_(sβ)/dt ofthe fixed coordinate system.

The first integrator 203 integrates the outputs of the first fixed fluxchange ratio calculation unit 201 to output the α axis flux λ_(sα) ofthe fixed coordinate system.

The second integrator 204 integrates the outputs of the second fixedflux change ratio calculation unit 202 to output the β axis flux λ_(sβ)of the fixed coordinate system.

The α axis flux λ_(sα) and β axis flux λ_(sβ) output by the firstintegrator 203 and the second integrator 204 are input to thetrigonometric function calculation unit 40. <Fixed Flux Error EstimationUnit 30>

The fixe flux error estimation unit 30 includes a first subtractor 301,a second subtractor 302, a first controller 303 and a second controller304 and performs the function of compensating for the estimated fixedcoordinate system α-β axis flux, and an error is compensated for by a PIcontroller and input to the fixed flux estimation unit 20.

The first subtractor 301 calculates the difference between the α axisflux instruction value λ_(sα)* of the fixed coordinate system input fromthe fixed flux instruction estimation unit 10 and the α axis flux λ_(sα)input from the fixed flux estimation unit 20.

The second subtractor 302 calculates the difference between the β axisflux instruction value λ_(sβ)* of the fixed coordinate system input fromthe fixed flux instruction estimation unit 10 and the β axis flux λ_(sβ)input from the fixed flux estimation unit 20.

The first controller 303 receives the difference from the firstsubtractor 301, performs proportional-integral (PI) control by theequation K_(Pα)+K_(Iα)/S (K_(Pα): proportional gain, K_(Iα): integralgain, S: complex variable) to adjust a gain and calculates the α axisflux error Δ_(sα) of the fixed coordinate system.

The second controller 304 receives the difference from the secondsubtractor 302, performs PI control by the equation K_(Pβ)+K_(Iβ)/S(K_(Pβ): proportional gain, K_(Iβ): integral gain, S: complex variable)to adjust a gain and calculates the β axis flux error Δ_(sβ) of thefixed coordinate system.

The α axis flux error Δ_(sα) and β axis flux error Δ_(sβ) are fed backto the fixe flux estimation unit 20.

<Trigonometric Function Calculation Unit 40>

The trigonometric function calculation unit 40 includes a firstarctangent unit 401, a second arctangent unit 402, and a rotation anglesubtraction unit 403.

The first arctangent unit 401 receives the d axis flux λ_(sd) of therotary coordinate system and the q axis flux λ_(sq) of the rotarycoordinate system from the fixed flux instruction estimation unit 10 andoutputs the angle θ_(dq) of λ_(d q) based on the d axis by using atrigonometric function arctangent.

The second arctangent unit 402 receives the α axis flux λ_(sα) of thefixed coordinate system and the β axis flux λ_(sβ) of the fixedcoordinate system from the fixed flux estimation unit 20 and outputs theangle θ_(αβ of λ) _(αβ) based on the α axis by using the trigonometricfunction arctangent.

The rotation angle subtraction unit 403 finds the difference between theangles θ_(αβ) and θ_(dq) to output the rotation angle θ, and therotation angle θ is fed back to the fixed flux instruction estimationunit 10.

When the rotation angle θ is found, it is possible to find the speedW_(e) of a rotor and thus the sensorless vector control system of thePMSM according to an embodiment receives the rotation angle θ and thespeed W_(e) from the rotation angle estimation unit 100 and controls thePMSM.

FIG. 4 is a block diagram representing a state in which the rotationangle estimation unit 100 according to an embodiment is applied to asensorless vector control system inverter-controlling a typical PMSM,through which it is possible to understand how the outputs of therotation angle estimation unit 100, the rotation angle θ and the speedW_(e) are input to a PMSM control unit 1.

The technical scope of an embodiment includes the sensorless vectorcontrol system of the PMSM to which the rotation angle estimation unit100 is applied.

Since the embodiment describes a method of finding the stator fluxvector and the rotor flux vector, the flux equation of a rotor circuitis coordinate-converted into the stator flux equation by the applying ofthe voltage equation of a stator circuit and the flux equation of therotor circuit and then the stator flux vector is compensated for tofinally find the stator flux vector and the rotor flux vector.

The angles θ_(αβ) and θ_(dq) are found by the applying of thetrigonometric function tan⁻¹ to the final stator flux vector and rotorflux vector and the location θ information on the PMSM is estimated byusing the equation θ=θ_(αβ)−θ_(dq).

Since the method is easy to implement, it is easy to actually apply itto a product and since the stator voltage equation and the rotorequation are together used, an estimated error in location informationat low and high speeds is minimized.

Also, the rotation angle estimation unit 100 according to an embodimentmay also be applied to a vector control system having location and speedsensors as a backup in addition to the sensorless vector control systemof the PMSM.

According to an embodiment, since the stator voltage equation and therotor equation are together used, it is possible to rapidly andaccurately estimate the rotation angle of a rotor at low and high speedsand by applying the estimated rotation angle to perform the sensorlessvector control of the PMSM, it is possible to provide a more reliableand economical sensorless vector control system of the PMSM.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within scope of the principles of thisdisclosure. More particularly, various variations and modifications arepossible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

What is claimed is:
 1. A rotation angle estimation module of a permanent magnetic synchronous motor (PMSM) for sensorless vector control of the PMSM, the rotation angle estimation module comprising: a fixed flux instruction estimation unit calculating a rotating flux (λ_(sd), λ_(sq))and a fixed flux instruction (λ_(sα)*, λ_(sβ)*) based on a rotation angle θ and the current (I_(sα), I_(sβ)) of a fixed coordinate system; a fixed flux estimation unit calculating a fixed flux (λ_(sα), λ_(sβ)) based on the voltage (V_(sα), V_(sβ)) of the fixed coordinate system, and the current (I_(sα), I_(sβ)) and fixed flux error (Δ_(sα), Δ_(sβ)) of the fixed coordinate system; a fixed flux error estimation unit using the difference between the fixed flux instruction (λ_(sα)*, λ_(sβ)*) and the fixed flux (λ_(sα), λ_(sβ)) to calculate the fixed flux error (Δ_(sα), Δ_(sβ)) and feed the errors back to the fixed flux estimation unit; and a trigonometric function calculation unit calculating the rotation angle θ, a distance that a rotor moves, based on the rotating flux (λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)).
 2. The rotation angle estimation module according to claim 1, wherein the trigonometric function calculation unit finally calculates the rotation angle θ and feeds a calculated angle back to the fixed flux instruction estimation unit.
 3. The rotation angle estimation module according to claim 1, wherein the fixed flux instruction estimation unit calculates the rotating flux (λ_(sd), λ_(sq)) based on the current (I_(sα), I_(sβ)) of the fixed coordinate system, the rotation angle θ, the inductance (L_(d), L_(q)) of a rotary coordinate system, and the flux λ_(PM) of a permanent magnet.
 4. The rotation angle estimation module according to claim 3, wherein the fixed flux instruction estimation unit compensates for the rotation angle θ by using the rotating flux (λ_(sd), λ_(sq)) to calculate a fixed flux instruction (λ_(sα)*, λ_(sβ)*).
 5. The rotation angle estimation module according to claim 1, wherein the fixed flux estimation unit receives the α axis voltage V_(sα) of the fixed coordinate system, the α axis current I_(sα) of the fixed coordinate system, and the α axis flux error Δ_(sα) of the fixed coordinate system to calculate an α axis flux change ratio dλ_(sα)/dt of the fixed coordinate system by using an equation dλ_(sα)/dt=V_(sα)−R_(s)I_(sα)+Δ_(sα)(R_(s): stator resistance), receives the β axis voltage V_(sβ) of the fixed coordinate system, the β axis current I_(sβ) of the fixed coordinate system, and the β axis flux error Δ_(sβ) of the fixed coordinate system to calculate the β axis flux change ratio dλ_(sβ)/dt of the fixed coordinate system by using the equation dλ_(sβ)/dt=V_(sβ)−R_(s)I_(sβ)+Δ_(sβ)(R_(s): stator resistance), integrates the α axis flux change ratio dλ_(sα)/dt of the fixed coordinate system to output the α axis flux λ_(sα), and integrates the output of the β axis flux change ratio dλ_(sβ)/dt of the fixed coordinate system to output the β axis flux λ_(sβ) of the fixed coordinate system.
 6. The rotation angle estimation module according to claim 1, wherein the fixed flux error estimation unit calculates the difference between the α axis flux instruction value λ_(sα)* of the fixed coordinate system input from the fixed flux instruction estimation unit and the α axis flux λ_(sα) input from the fixed flux estimation unit, calculates the difference between the β axis flux instruction value λ_(sβ)* of the fixed coordinate system input from the fixed flux instruction estimation unit and the β axis flux λ_(sβ) input from the fixed flux estimation unit, receives the difference from the α axis flux λ_(sα) to adjust a gain and calculate the α axis flux error Δ_(sα) of the fixed coordinate system, and receives the difference from the β axis flux λ_(sβ) to adjust a gain and calculate the β axis flux error Δ_(sβ) of the fixed coordinate system.
 7. The rotation angle estimation module according to claim 1, wherein the trigonometric function calculation unit: finds angels θ_(dq) and θ_(αβ) by the applying of a trigonometric function to the rotating flux (λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)), respectively, and outputs the rotation angle θ based on the angles θ_(dq) and θ_(αβ).
 8. The rotation angle estimation module according to claim 7, wherein the trigonometric function calculation unit: receives the d axis flux λ_(sd) of the rotary coordinate system and the q axis flux λ_(sq) of the rotary coordinate system from the fixed flux instruction estimation unit to output the angle θ_(dq) of λ_(d q) based on the d axis by using a trigonometric function arctangent, receives the α axis flux λ_(sα) of the fixed coordinate system and the β axis flux λ_(sβ) of the fixed coordinate system from the fixed flux estimation unit to output the angle θ_(αβ) of λ_(αβ) based on the α axis by using the trigonometric function arctangent, and finds the difference between the angles θ_(dq) and θ_(60 β) to output the rotation angle θ.
 9. An operating method of a rotation angle estimation module of a motor for sensorless vector control of a PMSM, the operating method comprising: calculating a rotating flux (λ_(sd), λ_(sq)) and a fixed flux instruction (λ_(sα)*, λ_(sβ)*) based on the current (I_(sα), I_(sβ)) of a fixed coordinate system and a rotation angle θ; calculating a fixed flux (λ_(sα), λ_(sβ)) based on the voltage (V_(sα), V_(sβ)) of the fixed coordinate system, and the current (I_(sα), I_(sβ)) and fixed flux error (Δ_(sα), Δ_(sβ)) of the fixed coordinate system, through a fixed flux estimation unit; using the difference between the fixed flux instruction (λ_(sα)*, λ_(sβ)*) and the fixed flux (λ_(sα), λ_(sβ)) to calculate the fixed flux error (Δ_(sα), Δ_(sβ)) and feed the errors back to the fixed flux estimation unit; and calculating the rotation angle θ, a distance that a rotor moves, based on the rotating flux (λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)).
 10. The operating method according to claim 9, further comprising finally calculating the rotation angle to feed a calculated angle back to the fixed flux instruction estimation unit.
 11. The operating method according to claim 9, wherein the calculating of the rotating flux (λ_(sd), λ_(sq)) and fixed flux instruction (λ_(sα)*, λ_(sβ)*) comprises calculating the rotating flux (λ_(sd), λ_(sq)) based on the current (I_(sα), I_(sβ)) of the fixed coordinate system, the rotation angle θ, the inductance (L_(d), L_(q)) of a rotary coordinate system, and the flux λ_(PM) of a permanent magnet.
 12. The operating method according to claim 11, wherein the calculating of the rotating flux (λ_(sd), λ_(sq)) and fixed flux instruction (λ_(sα)*, λ_(sβ)*) comprises compensating for the rotation angle θ by using the rotating flux to calculate the fixed flux instruction (λ_(sα)*, λ_(sβ)*).
 13. The operating method according to claim 9, wherein the calculating of the fixed flux (λ_(sα), λ_(sβ)) comprises: receiving the α axis voltage V_(sα) of the fixed coordinate system, the α axis current I_(sα) of the fixed coordinate system, and the α axis flux error Δ_(sα) of the fixed coordinate system to calculate an α axis flux change ratio dλ_(sα)/dt of the fixed coordinate system by using an equation dλ_(sα)/dt=V_(sα)−R_(s)I_(sα)+Δ_(sα)(R_(s): stator resistance); receiving the β axis voltage V_(sβ) of the fixed coordinate system, the β axis current I_(sβ) of the fixed coordinate system, and the β axis flux error Δ_(sβ) of the fixed coordinate system to calculate an β axis flux change ratio dλ_(sβ)/dt of the fixed coordinate system by using an equation dλ_(sβ)/dt=V_(sβ)−R_(s)I_(sβ)+Δ_(sβ)(R_(s): stator resistance); integrating the α axis flux change ratio dλ_(sα)/dt of the fixed coordinate system to output the α axis flux λ_(sα) of the fixed coordinate system; and integrating the outputs of the β axis flux change ratio dλ_(sβ)/dt of the fixed coordinate system to output the β axis flux λ_(sβ) of the fixed coordinate system.
 14. The operating method according to claim 9, wherein the calculating of the fixed flux error (Δ_(sα), Δ_(sβ)) comprises: calculating the difference between the α axis flux instruction value λ_(sα)* of the fixed coordinate system and the α axis flux λ_(sα) input from the fixed flux estimation unit, calculating the difference between the β axis flux instruction value λ_(sβ)* of the fixed coordinate system and the β axis flux λ_(sβ) input from the fixed flux estimation unit, receiving the difference from the α axis flux λ_(sα)to adjust a gain and calculate the α axis flux error Δ_(sα) of the fixed coordinate system; and receiving the difference from the β axis flux λ_(sβ) to adjust a gain and calculate the β axis flux error Δ_(sβ) of the fixed coordinate system.
 15. The operating method according to claim 9, wherein the calculating of the rotation angle θ comprises: obtaining angles θ_(dq) and θ_(αβ) by the applying of a trigonometric function to the rotating flux (λ_(sd), λ_(sq)) and the fixed flux (λ_(sα), λ_(sβ)), respectively; and outputting the rotation angle θ based on the angle (θ_(dq), θ_(αβ)).
 16. The operating method according to claim 15, wherein the outputting of the rotation angle θ based on the angles θ_(dq) and θ_(αβ) comprises: receiving the d axis flux λ_(sd) of the rotary coordinate system and the q axis flux λ_(sq) of the rotary coordinate system and outputting the angle θ_(dq) of λ_(dg) based on the d axis by using a trigonometric function arctangent, receiving the α axis flux λ_(sα) of the fixed coordinate system and the β axis flux λ_(sβ) of the fixed coordinate system and outputting the angle θ_(αβ) of λ_(αβ) based on the α axis by using the trigonometric function arctangent, and finds the difference between the angle θ_(αβ) and θ_(dq) to output the rotation angle θ. 